1. Field of the Invention
This invention relates to thermal storage methods and apparatus, and is particularly directed to thermal storage methods and apparatus whereby a movable manifold discharges a thermal transfer fluid, such as silicone oil, to trickle through a particulate solid thermal storage medium, such as a quantity of rocks, and to be collected thereafter for distribution or for recirculation in a manner such as to establish a vertical thermocline within said thermal storage medium, said thermocline being movable horizontally with said manifold.
2 Description of the Prior Art
In the current search for alternative sources of energy, considerable attention has been devoted to solar energy. Various techniques have been proposed for converting solar energy into thermal energy. Unfortunately, the prior art has taught no satisfactory method for storing thermal energy.
U.S. Pat. No. 3,369,541, issued Feb. 20, 1968 to Harry E. Thomason, discloses a prior art thermal storage system. However, in this system the liquid does not travel through the solid medium and does not provide a definitive thermocline.
U.S. Pat. No. 4,010,731, issued Mar. 8, 1977 to Henry Harrison, teaches a thermal storage system in which heat rises to the top of the solid medium only by convection. Moreover, a large quantity of thermal transfer fluid is required for Harrison's system, since he requires that the fluid completely fill all spaces between the solid medium.
U.S. Pat. No. 4,037,583, issued July 26, 1977 to Paul Bakun, teaches a thermal storage system employing separate manifolds for charging and extracting fluid. This requires that heat travel sideways through the bed by natural conduction and convection. This system also requires a large quantity of thermal transfer liquid and it appears unlikely that this system would provide a thermocline.
U.S. Pat. No. 4,059,226, issued Nov. 22, 1977 to David L. Atkinson, teaches a thermal storage system that uses only air and rocks. No liquids are used. This system must be completely charged with heat before any heat can be withdrawn. The Atkinson system would appear to be expensive, since it requires a plurality of tanks together with the piping and valves necessary to guide the heat transfer fluid to the appropriate tank.